This invention relates to a tie exchanger with a self-aligning tie clamp for replacing ties in a railroad track bed. More specifically, this invention relates to such a tie exchanger mountable on the back of a vehicle such as a truck or other road vehicle. (As used herein, a road vehicle is a vehicle which is designed for normal operation along roads, as opposed to vehicles limited to movement along rails and vehicles such as tractors, bulldozers, or backhoes designed for normal operation off of roads.)
In order to maintain railroad tracks in safe operating conditions, it is necessary to replace the ties periodically. The ties (made of wood, metal, or concrete) underneath the rails tend to wear out after an extended period of use.
Among the various machines which have been used for removing and inserting railroad ties is the machine described in U.S. Pat. No. 4,951,573 issued Aug. 28, 1990 to Harry Madison, one of the present inventors, and assigned to the assignee of the present application. That patent, hereby incorporated by reference, describes a tie remover/inserter machine which uses the vehicle of a conventional backhoe with various modifications.
Various other rail-bound vehicles having tie remover and inserter mechanisms mounted thereon have been used. Such vehicles are quite appropriate for use when replacing the ties over a relatively large section of rail roadbed. However, it may be expensive or difficult to bring in such a vehicle if a relatively small number of ties need replacement. For such situations, a railroad often has used a truck equipped with rail guide wheels and various hand tools to remove and insert ties. The rail guide wheels may be lowered so that a road vehicle, such as a truck, may travel along the rails until it reaches the location in need of repairs. Such a truck has often been equipped with a crane and winch to assist with handling the ties. Disadvantageously, exchanging ties in this manner is very labor intensive and slow.
Tie inserters have traditionally had clamps which may be used to grip the ties so that old ties may be removed from the roadbed and new ties may be inserted into the roadbed. Unfortunately, such tie clamps have had a great tendency to damage concrete ties because of the concave surfaces on such ties. In particular, tie clamps have had difficulty securely gripping ties, such as concrete ties, with concave surfaces or with irregular surfaces without damaging the ties.